Aside from the two groups noted, we need to consider the positive and negative effects the suggested changes to RPD would have on the safety and health community. Importantly, smaller employers with facilities in a single country have no reason to care what the rest of the world does with respiratory protection. My experience suggests they are concerned with protecting their workers with the least possible interference with production. Nonetheless, changing RPD classifications will require changes to their respiratory protection programs, along with the associated retraining, fit-testing, and other associated costs. The proposed RPD classification system is significantly more complex than those currently in use. Rather than asking, “Will employers and workers be able to make the transition from N95 to PC3 W1 bT F2 RPD?” as Mr. Colton does, I would ask, “Would there be a safety and health benefit to making this transition?” Complexity breeds confusion that can increase error. In addition, there is no technical basis for the complex particle filter and work rate components incorporated into the ISO classification system. (I have repeatedly asked for any supporting data and received none.) In truth, existing data show that particle respirator selection could be simplified without compromising protection. Time spent by employers making unnecessary work rate estimates for filter selection is time not available for other, productive work. Regarding the question “Will ISO respirator standards do away with APFs?” posed by the article’s subtitle, we again should ask if there would be a safety and health benefit to doing so. The ISO committees propose changing the term “assigned protection factor” to “protection level” (PL), which is not a problem in itself. However, the PLs are to be earned by RPD based on laboratory total inward leakage (TIL) testing. The PLs currently suggested in the ISO proposals are based on the range of existing European APFs and a safety factor based on “expert judgment.” In other words, educated guessing; no TIL test has ever been shown to correlate with workplace performance. In fairness to the ISO committee, the current proposal suggests using existing APFs until the PLs can be validated with workplace testing. As Mr. Colton notes, a number of OSHA’s APFs are based at least in part on workplace testing, and others are based on design analogies to the tested RPD. OSHA assigned APFs to respirator classes rather than TIL tests because existing data bear out that approach. It is illogical and potentially less protective to even consider PLs based on TIL tests for the sake of harmonization. The APF issue points to the need for more emphasis on workplace testing of existing RPD. In truth, real-world respirator performance of existing RPD is not as well understood as it should be. How can we predict performance for yet-to-be designed RPD if we don’t fully understand our current devices? We believe our design analogies are correct, but workplace testing would provide assurance. Aside from half-facepiece particle-filtering respirators, OSHA’s APFs are based on a very limited number of studies, and some of the studies available during rulemaking were quite old. Even Mr. Colton seems unaware that relatively recent work published in 2007 by JOEH has shown that full-facepiece respirators in the U.S. have “come close to” (or exceeded) the European nominal protection factor of 1000 (I was coauthor of the study). As that study suggests, it is possible that some of the existing APFs may actually be too low. The ISO respirator standards need more consideration by and input from practicing industrial hygienists. Existing data show that our current RPD, regulations, and practices are protecting workers. This is their purpose. Most members of the ISO standards committees are not IHs, and very few have experience managing respiratory protection or other safety and health programs. It is not clear to me they appreciate that changes to RPD and respirator program requirements would take time and resources away from other components of an organization’s safety and health program. If those changes don’t significantly enhance worker protection or comfort, they should not be implemented. Given that several countries’ standards organizations and some respirator manufacturers have invested substantial money and time in ISO standards development, it is likely there will be significant pressure to adopt, at a minimum, ISO-compliant RPD. That is acceptable only if the ISO requirements for those devices are based on the best available data, and benefit workers as well as overall safety and health programs. The industrial hygiene community is uniquely qualified to guide ISO in the development of protective yet practical RPD standards. LARRY JANSSEN, CIH, is an industrial hygiene consultant in Stillwater, Minn. He can be reached at (651) 430-0815 or lljanssen@centurylink.net.